Oil-resistant agent for paper

ABSTRACT

A paper oil-resistant agent which is added to the interior of paper and includes (1) a non-fluorine polymer and (2) at least one type of particles selected from inorganic particles or organic particles, the amount of the particles (2) being 1-99.9 wt % of the total weight of the non-fluorine polymer (1) and the particles (2). Also disclosed is an oil-resistant paper including the paper oil-resistant agent and a method for producing the oil-resistant paper.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Rule 53(b) Continuation of InternationalApplication No. PCT/JP2020/020972 filed May 27, 2020, claiming prioritybased on Japanese Patent Application No. 2019-099463 filed May 28, 2019,the respective disclosures of which are incorporated herein by referencein their entirety.

TECHNICAL FIELD

The present disclosure relates to an oil-resistant agent for paper, andpaper treated with the oil-resistant agent for paper.

BACKGROUND ART

Paper may be required to have oil resistance.

For example, food packaging and food containers which are made of paperare required to prevent water and oil contained in food from oozing out.Accordingly, an oil-resistant agent is internally or externally appliedto the paper.

Several proposals have been made to impart oil resistance to paper.

Patent Literature 1 (JP 2015-129365 A) discloses a method of forming acellulose article, comprising: attaching cellulose fibers to a compoundcomprising an aqueous dispersion comprising at least one polymerselected from the group consisting of an ethylene thermoplastic polymer,a propylene thermoplastic polymer, and a mixture thereof; at least onepolymer stabilizer; and water.

Patent Literature 2 (WO 2015/008868 A1) discloses a fine cellulose fibersheet comprising fine cellulose fibers having an average fiber diameterof 2 nm or more and 1,000 nm or less, wherein a weight ratio of the finecellulose fibers is 50% to 99% by weight, and the block polyisocyanateaggregate is contained in a weight ratio of 1 to 100% by weight, basedon the fine cellulose fiber weight.

Patent Document 3 (JP 2004-148307 A) discloses a method for producing acoated support comprising: a) forming a composite multilayerfree-flowing curtain comprising at least two layers imparting barrierfunctionalities, and b) bringing the curtain into contact with acontinuous web support to give a coated support.

CITATION LIST Patent Literature Patent Literature 1

JP 2015-129365 A

Patent Literature 2

WO 2015/008868 A1

Patent Literature 3

JP 2004-148307 A

SUMMARY OF INVENTION Technical Problem

An object of the present disclosure is to provide an oil-resistant agentcapable of imparting excellent oil resistance to paper.

Solution to Problem

The present disclosure relates to an oil-resistant agent comprising (1)a fluorine-free polymer and (2) particles selected from inorganicparticles and/or organic particles. In the treatment of the paper, theoil-resistant agent may be externally or internally added, andpreferably the oil-resistant agent is internally added.

Preferable embodiments of the present disclosure are as follows:

[1]

A paper oil-resistant agent which is added to interior of paper,comprising:

-   -   (1) a fluorine-free polymer, and    -   (2) at least one type of particles selected from inorganic        particles or organic particles,

wherein an amount of the particles (2) is 1 to 99.9% by weight, based onthe total weight of the fluorine-free polymer (1) and the particles (2).

[2]

The paper oil-resistant agent according to [1], wherein thefluorine-free polymer (1) is an acrylic polymer.

[3]

The paper oil-resistant agent according to [1] or [2], wherein thefluorine-free polymer has a repeating unit formed from an acrylicmonomer having a long-chain hydrocarbon group (a), and

the acrylic monomer having a long-chain hydrocarbon group (a) is amonomer represented by formula:

CH₂═C(—X¹)—C(═O)—Y¹(R¹)_(k)

wherein

R¹ each is independently a hydrocarbon group having 7 to 40 carbonatoms,

X¹ is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y¹ is a divalent to a tetravalent group composed of at least oneselected from a hydrocarbon group having one carbon atom, —C₆H₄—, —O—,—C(═O)—, —S(═O)₂—, or —NH—, provided that a hydrocarbon group isexcluded, and

k is 1 to 3.

[4]

The paper oil-resistant agent according to [3], wherein, in the acrylicmonomer having a long-chain hydrocarbon group (a), X¹ is a hydrogen atomor a methyl group.

[5]

The paper oil-resistant agent according to any one of [1] to [4],wherein, in the acrylic monomer having a long-chain hydrocarbon group(a), the long-chain hydrocarbon group has 18 or more carbon atoms.

[6]

The paper oil-resistant agent according to any one of [3] to [5],wherein

the acrylic monomer having a long-chain hydrocarbon group (a) is:(a1) an acrylic monomer represented by formula:

CH₂═C(—X⁴)—C(═O)—Y²—R²

wherein

R² is a hydrocarbon group having 7 to 40 carbon atoms,

X⁴ is a hydrogen atom, a monovalent organic group, or a halogen atom,and

Y² is —O— or —NH—, and/or

(a2) an acrylic monomer represented by formula:

CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_(n)

wherein

R³ each is independently a hydrocarbon group having 7 to 40 carbonatoms,

X⁵ is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y³ is —O— or —NH—,

Y⁴ each is independently a group composed of at least one selected froma direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,

Z is a direct bond or a divalent or trivalent hydrocarbon group having 1to 5 carbon atoms, and

n is 1 or 2.

[7]

The paper oil-resistant agent according to any one of [3] to [6],wherein

the acrylic monomer having a hydrophilic group (b) is at least oneoxyalkylene (meth)acrylate represented by formula:

CH₂═CX²C(═O)—O—(RO)_(n)—X³  (b1),

CH₂═CX²C(═O)—O—(RO)_(n)—C(═O)CX²═CH₂  (b2), or

CH₂═CX²C(═O)—NH—(RO)_(n)—X³  (b3)

wherein

X² is a hydrogen atom or a methyl group,

X³ is a hydrogen atom or an unsaturated or saturated hydrocarbon grouphaving 1 to 22 carbon atoms,

R each is independently an alkylene group having 2 to 6 carbon atoms,and

n is an integer of 1 to 90.

[8]

The paper oil-resistant agent according to any one of [3] to [7],wherein the fluorine-free polymer further comprises a repeating unitformed from (c) a monomer having an olefinic carbon-carbon double bondand having an anion donating group or a cation donating group, otherthan the monomers (a) and (b).

[9]

The paper oil-resistant agent according to [8], wherein the aniondonating group is a carboxyl group, or the cation donating group is anamino group.

[10]

The paper oil-resistant agent according to any one of [3] to [9],wherein an amount of the repeating unit formed from the acrylic monomerhaving a long-chain hydrocarbon group (a) is 30 to 90% by weight, basedon a copolymer, and an amount of the repeating unit formed from theacrylic monomer having a hydrophilic group (b) is 5 to 70% by weight,based on the copolymer.

[11]

The paper oil-resistant agent according to any one of [1] to [10],wherein the inorganic particles are made of at least one selected fromcalcium carbonate, talc, kaolin, clay, mica, aluminum hydroxide, bariumsulfate, calcium silicate, calcium sulfate, silica, zinc carbonate, zincoxide, titanium oxide, bentonite, and white carbon, and

the organic particles are made of at least one selected frompolysaccharides and thermoplastic resins.[12]

The paper oil-resistant agent according to any one of [1] to [11],wherein the organic particles are insoluble in water at 40° C.

[13]

The paper oil-resistant agent according to any one of [1] to [12],wherein the inorganic particles are calcium carbonate, and the organicparticles are starch.

[14]

The paper oil-resistant agent according to any one of [1] to [13],wherein the particle (2) comprises the organic particles.

[15]

The paper oil-resistant agent according to any one of [1] to [14],further comprising a liquid medium which is water or a mixture of waterand an organic solvent.

[16]

Oil-resistant paper comprising the paper oil-resistant agent accordingto any one of [1] to [15] inside the paper.

[17]

The oil-resistant paper according to [16], which is a molded pulpproduct.

[18]

The oil-resistant paper according to [16] or [17], which is a foodpackaging material or a food container.

[19]

A method for producing oil-resistant paper, comprising:

preparing a formulated pulp slurry by adding the oil-resistant agentaccording to any one of [1] to [15] to a slurry in which pulp isdispersed in an aqueous medium, making an oil-resistant paperintermediate, followed by dehydrating and then drying to obtain theoil-resistant paper.

Advantageous Effects of Invention

In the oil-resistant agent, the fluorine-free polymer is favorablydispersed in an aqueous medium, particularly water.

The oil-resistant agent imparts high oil resistance to paper. Theoil-resistant agent can impart high water resistance and high gasbarrier properties.

DESCRIPTION OF EMBODIMENT

The oil-resistant agent comprises (1) a fluorine-free polymer, and (2)particles. The oil-resistant agent may be a one-, two-, or three-partliquid. The one-part liquid is a liquid comprising the fluorine-freepolymer (1) and the particles (2). The two-part liquid (two components)is a combination of a liquid comprising fluorine-free polymer (1) and aliquid comprising the particles (2) (or only particles (2)). In thethree-part liquid (three components), a liquid comprising an additivefor paper is added for use. The liquid comprising the particles (2) maybe a solid (for example, particles only).

(1) Fluorine-Free Polymer

The fluorine-free polymer may be, for example, an acrylic polymer,polyester polymer, polyether polymer, silicone polymer, or urethanepolymer. A polymer having an ester bond, an amide bond, and/or aurethane bond is preferable. Particularly, an acrylic polymer (i.e., afluorine-free acrylic polymer) is preferable. The acrylic polymerpreferably has an ester bond and/or an amide bond.

The fluorine-free polymer may be a homopolymer or a copolymer. Thefluorine-free polymer is preferably a copolymer.

A homopolymer has only a repeating unit formed from one monomer. Thehomopolymer is preferably formed only from an acrylic monomer having along-chain hydrocarbon group having 7 to 40 carbon atoms.

A copolymer has repeating units formed from two or more monomers.

The fluorine-free polymer preferably has:

(a) a repeating unit formed from an acrylic monomer having a long-chainhydrocarbon group having 7 to 40 carbon atoms, and(b) a repeating unit formed from an acrylic monomer having a hydrophilicgroup.

Moreover, the fluorine-free polymer preferably has a repeating unitformed of (c) a monomer having an ion donating group in addition to themonomers (a) and (b).

The fluorine-free polymer may have a repeating unit formed from (d)another monomer, in addition to the monomers (a), (b), and (c).

(a) Acrylic Monomer Having Long-Chain Hydrocarbon Group

The acrylic monomer having a long-chain hydrocarbon group (a) has along-chain hydrocarbon group having 7 to 40 carbon atoms. The long-chainhydrocarbon group having 7 to 40 carbon atoms is preferably a linear orbranched hydrocarbon group having 7 to 40 carbon atoms. The number ofcarbon atoms of the long-chain hydrocarbon group is preferably 10 to 40,such as 12 to 30, particularly 15 to 30. Alternatively, the number ofcarbon atoms of the long-chain hydrocarbon group may be 18 to 40 carbonatoms.

The acrylic monomer having a long-chain hydrocarbon group (a) ispreferably a monomer represented by formula:

CH₂═C(—X¹)—C(═O)—Y¹(R¹)_(k)

wherein

R¹ each is independently a hydrocarbon group having 7 to 40 carbonatoms,

X¹ is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y¹ is a divalent to tetravalent group composed of at least one selectedfrom a hydrocarbon group having one carbon atom (particularly, —CH₂—,—CH═), —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—, provided that ahydrocarbon group is excluded, and

k is 1 to 3.

X¹ may be a hydrogen atom, a methyl group, halogen excluding a fluorineatom, a substituted or unsubstituted benzyl group, or a substituted orunsubstituted phenyl group. Examples of X¹ include a hydrogen atom, amethyl group, a chlorine atom, a bromine atom, an iodine atom, and acyano group. X¹ is preferably a hydrogen atom, a methyl group, or achlorine atom. X¹ is particularly preferably a hydrogen atom.

Y¹ is a divalent to tetravalent group. Y¹ is preferably a divalentgroup.

Y¹ is preferably a group composed of at least one selected from ahydrocarbon group having one carbon atom, —C₆H₄—, —O—, —C(═O)—,—S(═O)₂—, or —NH—, provided that a hydrocarbon group is excluded.Examples of the hydrocarbon group having one carbon atom include —CH₂—,—CH═ having a branched structure, and —C═ having a branched structure.

Y¹ may be —Y′—, —Y′—Y′—, —Y′—C(═O)—, —C(═O)—Y′—, —Y′—C(═O)—Y′—, —Y′—R′—,—Y′—R′—Y′—, —Y′—R′—Y′—C(═O)—, —Y′—R′—C(═O)—Y′—, —Y′—R′—Y′—C(═O)—Y′—, or—Y′—R′—Y′—R′— wherein

Y′ is a direct bond, —O—, —NH—, or —S(═O)₂—, and

R′ is —(CH₂)_(m)— wherein m is an integer of 1 to 5, or —C₆H₄— (aphenylene group)

Specific examples of Y¹ include —O—, —NH—, —O—C(═O)—, —C(═O)—NH—,—NH—C(═O)—, —O—C(═O)—NH—, —NH—C(═O)—O—, —NH—C(═O)—NH—, —O—C₆H₄—,—O—(CH₂)_(m)—O—, —NH—(CH₂)_(m)—NH—, —O—(CH₂)_(m)—NH—, —NH—(CH₂)_(m)—O—,—O—(CH₂)_(m)—O—C(═O)—, —O—(CH₂)_(m)—C(═O)—O—, —NH—(CH₂)_(m)—O—C(═O)—,—NH—(CH₂)_(m)—C(═O)—O—, —O—(CH₂)_(m)—O—C(═O)—NH—,—O—(CH₂)_(m)—NH—C(═O)—O—, —O—(CH₂)_(m)—C(═O)—NH—,—O—(CH₂)_(m)—NH—C(═O)—, —O—(CH₂)_(m)—NH—C(═O)—NH—, —O—(CH₂)_(m)—O—C₆H₄—,—O—(CH₂)_(m)—NH—S(═O)₂—, —O—(CH₂)_(m)—S(═O)₂—NH—,—NH—(CH₂)_(m)—O—C(═O)—NH—, —NH—(CH₂)_(m)—NH—C(═O)—O—,—NH—(CH₂)_(m)—C(═O)—NH—, —NH—(CH₂)_(m)—NH—C(═O)—,—NH—(CH₂)_(m)—NH—C(═O)—NH—, —NH—(CH₂)_(m)—O—C₆H₄—,—NH—(CH₂)_(m)—NH—C₆H₄—, —NH—(CH₂)_(m)—NH—S(═O)₂—, or—NH—(CH₂)_(m)—S(═O)₂—NH—, wherein m is 1 to 5, particularly 2 or 4.

Y¹ is preferably —O—, —NH—, —O—(CH₂)_(m)—O—C(═O)—,—O—(CH₂)_(m)—NH—C(═O)—, —O—(CH₂)_(m)—O—C(═O)—NH—,—O—(CH₂)_(m)—NH—C(═O)—O—, —O—(CH₂)_(m)—NH—C(═O)—NH—,—O—(CH₂)_(m)—NH—S(═O)₂—, —O—(CH₂)_(m)—S(═O)₂—NH—,—NH—(CH₂)_(m)—NH—S(═O)₂—, or —NH—(CH₂)_(m)—S(═O)₂—NH— wherein m is aninteger of 1 to 5, particularly 2 or 4. Y¹ is more preferably —O— or—O—(CH₂)_(m)—NH—C(═O)—, particularly —O—(CH₂)_(m)—NH—C(═O)—.

R¹ is preferably a linear or branched hydrocarbon group. The hydrocarbongroup may be particularly a linear hydrocarbon group. The hydrocarbongroup is preferably an aliphatic hydrocarbon group, particularly asaturated aliphatic hydrocarbon group, and especially an alkyl group.The number of carbon atoms of the hydrocarbon group is preferably 12 to30, such as 16 to 26 or 15 to 26, particularly 18 to 22 or 17 to 22.

Examples of the acrylic monomer having a long-chain hydrocarbon group(a) include:

(a1) an acrylic monomer represented by formula:

CH₂═C(—X⁴)—C(═O)—Y²—R²

wherein

R² is a hydrocarbon group having 7 to 40 carbon atoms,

X⁴ is a hydrogen atom, a monovalent organic group, or a halogen atom,and

Y² is —O— or —NH—, and

(a2) an acrylic monomer represented by formula:

CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_(n)

wherein

R³ each is independently a hydrocarbon group having 7 to 40 carbonatoms,

X⁵ is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y³ is —O— or —NH—,

Y⁴ each is independently a group composed of at least one selected froma direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,

Z is a divalent or trivalent hydrocarbon group having 1 to 5 carbonatoms, and

n is 1 or 2.

(a1) Acrylic Monomer

The acrylic monomer (a1) is a compound represented by formula:

CH₂═C(—X⁴)—C(═O)—Y²—R²

wherein

R² is a hydrocarbon group having 7 to 40 carbon atoms,

X⁴ is a hydrogen atom, a monovalent organic group, or a halogen atom,and

Y² is —O— or —NH—.

The acrylic monomer (a1) is a long-chain acrylate ester monomer whereinY² is —O— or a long-chain acrylamide monomer wherein Y² is —NH—.

R² is preferably an aliphatic hydrocarbon group, particularly asaturated aliphatic hydrocarbon group, and especially an alkyl group. InR², the number of carbon atoms of the hydrocarbon group is preferably 12to 30, such as 16 to 26, particularly 18 to 22.

X⁴ may be a hydrogen atom, a methyl group, halogen excluding a fluorineatom, a substituted or unsubstituted benzyl group, or a substituted orunsubstituted phenyl group, and is preferably a hydrogen atom, a methylgroup, or a chlorine atom.

Preferable specific examples of the long-chain acrylate ester monomerinclude lauryl (meth)acrylate, stearyl (meth)acrylate, icosyl(meth)acrylate, behenyl (meth)acrylate, stearyl α-chloroacrylate, icosylα-chloroacrylate, and behenyl α-chloroacrylate.

Preferable specific examples of the long-chain acrylamide monomerinclude stearyl (meth)acrylamide, icosyl (meth)acrylamide, and behenyl(meth)acrylamide.

(a2) Acrylic Monomer

The acrylic monomer (a2) is a monomer different from the acrylic monomer(a1). The acrylic monomer (a2) is (meth)acrylate or (meth)acrylamidehaving a group composed of at least one selected from —O—, —C(═O)—,—S(═O)₂—, or —NH—.

The acrylic monomer (a2) may be a compound represented by formula:

CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_(n)

wherein

R³ each is independently a hydrocarbon group having 7 to 40 carbonatoms,

X⁵ is a hydrogen atom, a monovalent organic group, or a halogen atom,

Y³ is —O— or —NH—,

Y⁴ each is independently a group composed of at least one selected froma direct bond, —O—, —C(═O)—, —S(═O)₂—, or —NH—,

Z is a direct bond or a divalent or trivalent hydrocarbon group having 1to 5 carbon atoms, and

n is 1 or 2.

R³ is preferably an aliphatic hydrocarbon group, particularly asaturated aliphatic hydrocarbon group, and especially an alkyl group. InR³, the number of carbon atoms of the hydrocarbon group is preferably 12to 30, such as 16 to 26 or 15 to 26, particularly 18 to 22 or 17 to 22.

X⁵ may be a hydrogen atom, a methyl group, halogen excluding a fluorineatom, a substituted or unsubstituted benzyl group, or a substituted orunsubstituted phenyl group, and is preferably a hydrogen atom, a methylgroup, or a chlorine atom.

Y⁴ may be —Y′—, —Y′—Y′—, —Y′—C(═O)—, —C(═O)—Y′—, —Y′—C(═O)—Y′—, —Y′—R′—,—Y′—R′—Y′—, —Y′—R′—Y′—C(═O)—, —Y′—R′—C(═O)—Y′—, —Y′—R′—Y′—C(═O)—Y′—, or—Y′—R′—Y′—R′— wherein

Y′ each is independently a direct bond, —O—, —NH—, or —S(═O)₂—, and

R′ is —(CH₂)_(m)— wherein m is an integer of 1 to 5, a linearhydrocarbon group having 1 to 5 carbon atoms and an unsaturated bond, ahydrocarbon group having 1 to 5 carbon atoms and a branched structure,or —(CH₂)_(l)—C₆H₄—(CH₂)_(l)— wherein l each is independently an integerof 0 to 5, and —C₆H₄— is a phenylene group.

Specific examples of Y⁴ include a direct bond, —O—, —NH—, —O—C(═O)—,—C(═O)—O—, —C(═O)—NH—, —NH—C(═O)—, —NH—S(═O)₂—, —S(═O)₂—NH—,—O—C(═O)—NH—, —NH—C(═O)—O—, —NH—C(═O)—NH—, —O—C₆H₄—, —NH—C₆H₄—,—O—(CH₂)_(m)—O—, —NH—(CH₂)_(m)—NH—, —O—(CH₂)_(m)—NH—, —NH—(CH₂)_(m)—O—,—O—(CH₂)_(m)—O—C(═O)—, —O—(CH₂)_(m)—C(═O)—O—, —NH—(CH₂)_(m)—O—C(═O)—,—NH—(CH₂)_(m)—C(═O)—O—, —O—(CH₂)_(m)—O—C(═O)—NH—,—O—(CH₂)_(m)—NH—C(═O)—O—, —O—(CH₂)_(m)—C(═O)—NH—,—O—(CH₂)_(m)—NH—C(═O)—, —O—(CH₂)_(m)—NH—C(═O)—NH—, —O—(CH₂)_(m)—O—C₆H₄—, —NH—(CH₂)_(m)—O—C(═O)—NH—, —NH—(CH₂)_(m)—NH—C(═O)—O—,—NH—(CH₂)_(m)—C(═O)—NH—, —NH—(CH₂)_(m)—NH—C(═O)—,—NH—(CH₂)_(m)NH—C(═O)—NH—, —NH—(CH₂)_(m)—O—C₆H₄—, —NH—(CH₂)_(m)—NH—C₆H₄—wherein m is an integer of 1 to 5.

Y⁴ is preferably —O—, —NH—, —O—C(═O)—, —C(═O)—O—, —C(═O)—NH—,—NH—C(═O)—, —NH—S(═O)₂—, —S(═O)₂—NH—, —O—C(═O)—NH—, —NH—C(═O)—O—,—NH—C(═O)—NH—, or —O—C₆H₄—. Y⁴ is more preferably —NH—C(═O)—,—C(═O)—NH—, —O—C(═O)—NH—, —NH—C(═O)—O—, or —NH—C(═O)—NH—.

Z is a direct bond or a divalent or trivalent hydrocarbon group having 1to 5 carbon atoms, and may have a linear structure or a branchedstructure. The number of carbon atoms of Z is preferably 2 to 4,particularly 2. Specific examples of Z include a direct bond, —CH₂—,—CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂—, —CH₂CH═ havinga branched structure, —CH₂(CH—)CH₂— having a branched structure,—CH₂CH₂CH═ having a branched structure, —CH₂CH₂CH₂CH₂CH═ having abranched structure, —CH₂CH₂(CH—)CH₂— having a branched structure, and—CH₂CH₂CH₂CH═ having a branched structure.

Z is preferably not a direct bond, and Y⁴ and Z are simultaneously notdirect bonds.

The acrylic monomer (a2) is preferablyCH₂═C(—X⁵)—C(═O)—O—(CH₂)_(m)—NH—C(═O)—R³,CH₂═C(—X⁵)—C(═O)—O—(CH₂)_(m)—O—C(═O)—NH—R³,CH₂═C(—X⁵)—C(═O)—O—(CH₂)_(m)NH—C(═O)—O—R³, orCH₂═C(—X⁵)—C(═O)—O—(CH₂)_(m)NH—C(═O)—NH—R³,

wherein R³ and X⁵ are as defined above.

The acrylic monomer (a2) is particularly preferablyCH₂═C(—X⁵)—C(═O)—O—(CH₂)_(m)NH—C(═O)—R³.

The acrylic monomer (a2) can be produced by reacting hydroxyalkyl(meth)acrylate or hydroxyalkyl (meth)acrylamide with long-chain alkylisocyanate. Examples of the long-chain alkyl isocyanate include laurylisocyanate, myristyl isocyanate, cetyl isocyanate, stearyl isocyanate,oleyl isocyanate, and behenyl isocyanate.

Alternatively, the acrylic monomer (a2) can also be produced by reacting(meth)acrylate having an isocyanate group in a side chain, such as2-methacryloyloxyethyl methacrylate, with long-chain alkylamine orlong-chain alkyl alcohol. Examples of the long-chain alkylamine includelaurylamine, myristylamine, cetylamine, stearylamine, oleylamine, andbehenylamine. Examples of the long-chain alkyl alcohol include laurylalcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleylalcohol, and behenyl alcohol.

Preferable examples of the long-chain hydrocarbon group-containingacrylic monomer are as follows:

stearyl (meth)acrylate, behenyl (meth)acrylate, stearylα-chloroacrylate, behenyl α-chloroacrylate;

stearyl (meth)acrylamide, behenyl (meth)acrylamide;

wherein n is a number of 7 to 40, and m is a number of 1 to 5.

The compounds of the above chemical formulae are acrylic compounds inwhich the α-position is a hydrogen atom, and specific examples may bemethacrylic compounds in which the α-position is a methyl group andα-chloroacrylic compounds in which the α-position is a chlorine atom.

The melting point of the acrylic monomer having a long-chain hydrocarbongroup (a) is preferably 10° C. or higher, and more preferably 25° C. orhigher.

The acrylic monomer having a long-chain hydrocarbon group (a) ispreferably an acrylate in which X¹, X⁴, and X³ are hydrogen atoms.

The acrylic monomer (a2) is preferably an amide group-containing monomerrepresented by formula:

R¹²—C(═O)—NH—R¹³—O—R¹¹ wherein

R¹¹ is an organic residue having an ethylenically unsaturatedpolymerizable group,

R¹² is a hydrocarbon group having 7 to 40 carbon atoms, and

R¹³ is a hydrocarbon group having 1 to 5 carbon atoms.

R¹¹ is an organic residue having an ethylenically unsaturatedpolymerizable group, and is not limited as long as there is acarbon-carbon double bond. Specific examples include organic residueshaving an ethylenically unsaturated polymerizable group such as—C(═O)CR¹⁴═CH₂, —CHR¹⁴═CH₂, and —CH₂CHR¹⁴═CH₂, and R¹⁴ is a hydrogenatom or an alkyl group having 1 to 4 carbon atoms. R¹¹ may have variousorganic groups other than the ethylenically unsaturated polymerizablegroup, e.g., organic groups such as chain hydrocarbons, cyclichydrocarbons, polyoxyalkylene groups, and polysiloxane groups, and theseorganic groups may be substituted with various substituents. R¹¹ ispreferably —C(═O)CR¹⁴═CH₂.

R¹² is a hydrocarbon group having 7 to 40 carbon atoms and preferably analkyl group, such as a chain hydrocarbon group or a cyclic hydrocarbongroup. Among them, a chain hydrocarbon group is preferable, and a linearsaturated hydrocarbon group is particularly preferable. The number ofcarbon atoms of R¹² is 7 to 40, preferably 11 to 27, and particularlypreferably 15 to 23.

R¹³ is a hydrocarbon group having 1 to 5 carbon atoms, and preferably analkyl group. The hydrocarbon group having 1 to 5 carbon atoms may beeither linear or branched, may have an unsaturated bond, and ispreferably linear. The number of carbon atoms of R¹³ is preferably 2 to4, and particularly preferably 2. R¹³ is preferably an alkylene group.

The amide group-containing monomer may be a monomer having one type ofR¹² (for example, a compound in which R¹² has 17 carbon atoms) or amonomer having a combination of multiple types of R¹² (for example, amixture of a compound in which R¹² has 17 carbon atoms and a compound inwhich R¹² has 15 carbon atoms)

An example of the amide group-containing monomer is carboxylic acidamide alkyl (meth)acrylate.

Specific examples of the amide group-containing monomer include palmiticacid amide ethyl (meth)acrylate, stearic acid amide ethyl(meth)acrylate, behenic acid amide ethyl (meth)acrylate, myristic acidamide ethyl (meth)acrylate, lauric acid amide ethyl (meth)acrylate,isostearic acid ethylamide (meth)acrylate, oleic acid ethylamide(meth)acrylate, tert-butylcyclohexylcaproic acid amide ethyl(meth)acrylate, adamantanecarboxylic acid ethylamide (meth)acrylate,naphthalenecarboxylic acid amide ethyl (meth)acrylate,anthracenecarboxylic acid amide ethyl (meth)acrylate, palmitic acidamide propyl (meth)acrylate, stearic acid amide propyl (meth)acrylate,palmitic acid amide ethyl vinyl ether, stearic acid amide ethyl vinylether, palmitic acid amide ethyl allyl ether, stearic acid amide ethylallyl ether, and mixtures thereof.

The amide group-containing monomer is preferably stearic acid amideethyl (meth)acrylate. The amide group-containing monomer may be amixture comprising stearic acid amide ethyl (meth)acrylate. In a mixturecomprising stearic acid amide ethyl (meth)acrylate, the amount ofstearic acid amide ethyl (meth)acrylate is, for example, 55 to 99% byweight, preferably 60 to 85% by weight, and more preferably 65 to 80% byweight, based on the weight of the entirety of the amidegroup-containing monomer, and the remainder of the monomer may be, forexample, palmitic acid amide ethyl (meth)acrylate.

(b) Acrylic Monomer Having Hydrophilic Group

The acrylic monomer having a hydrophilic group (b) is a monomerdifferent from the monomer (a), and is a hydrophilic monomer. Thehydrophilic group is preferably an oxyalkylene group (the number ofcarbon atoms of the alkylene group is 2 to 6). Particularly, the acrylicmonomer having a hydrophilic group (b) is preferably polyalkylene glycolmono(meth)acrylate, polyalkylene glycol di(meth)acrylate, and/orpolyalkylene glycol mono(meth)acrylamide. Polyalkylene glycolmono(meth)acrylate, polyalkylene glycol di(meth)acrylate, andpolyalkylene glycol mono(meth)acrylamide are preferably thoserepresented by general formulae:

CH₂═CX²C(═O)—O—(RO)_(n)—X³  (b1),

CH₂═CX²C(═O)—O—(RO)_(n)—C(═O)CX²═CH₂  (b2), or

CH₂═CX²C(═O)—NH—(RO)_(n)—X³  (b3)

wherein,

X² each is independently a hydrogen atom or a methyl group,

X³ each is independently is a hydrogen atom or an unsaturated orsaturated hydrocarbon group having 1 to 22 carbon atoms,

R each is independently an alkylene group having 2 to 6 carbon atoms,and

n is an integer of 1 to 90. n may be, for example, 1 to 50, particularly1 to 30, and especially 1 to 15 or 2 to 15. Alternatively, n may be, forexample, 1.

R may be a linear or branched alkylene group such as a group representedby formula —(CH₂)_(x)— or —(CH₂)_(x1)—(CH(CH₃))_(x2)— wherein x1 and x2are 0 to 6 such as 2 to 5, and the sum of x1 and x2 is 1 to 6; and theorder of —(CH₂)_(x1)— and —(CH(CH₃))_(x2)— is not limited to the formulashown, and may be random.

In —(RO)_(n)—, there may be two or more types (such as 2 to 4 types,particularly 2 types) of R, and thus —(RO)_(n)— may be a combination of,for example, —(R¹O)_(n1)— and —(R²O)_(n2)— wherein R¹ and R² aremutually different and an alkylene group having 2 to 6 carbon atoms, n1and n2 are a number of 1 or more, and the sum of n1 and n2 is 2 to 90.

R in general formulae (b1), (b2), and (b3) is particularly preferably anethylene group, a propylene group, or a butylene group. R in generalformulae (b1), (b2), and (b3) may be a combination of two or more typesof alkylene groups. In this case, at least one R is preferably anethylene group, a propylene group, or a butylene group. Examples of thecombination of R include a combination of an ethylene group/a propylenegroup, a combination of an ethylene group/a butylene group, and acombination of a propylene group/a butylene group. The monomer (b) maybe a mixture of two or more types. In this case, in at least one monomer(b), R in general formula (b1), (b2), or (b3) is preferably an ethylenegroup, a propylene group, or a butylene group. Polyalkylene glycoldi(meth)acrylate represented by general formula (b2) is not preferablyused solely as the monomer (b), and is preferably used in combinationwith the monomer (b1). In this case as well, the compound represented bygeneral formula (b2) is preferably less than 30% by weight in themonomer (b) used.

Specific examples of the acrylic monomer having a hydrophilic group (b)include, but are not limited to, the following.

CH₂═CHCOO—CH₂CH₂O—HCH₂═CHCOO—CH₂CH₂CH₂O—HCH₂═CHCOO—CH₂CH(CH₃)O—HCH₂═CHCOO—CH(CH₃) CH₂O—HCH₂═CHCOO—CH₂CH₂CH₂CH₂O—HCH₂═CHCOO—CH₂CH₂CH(CH₃)O—HCH₂═CHCOO—CH₂CH(CH₃) CH₂O—HCH₂═CHCOO—CH(CH₃) CH₂CH₂O—HCH₂═CHCOO—CH₂CH(CH₂CH₃)O—HCH₂═CHCOO—CH₂C(CH₃)₂O—HCH₂═CHCOO—CH(CH₂CH₃) CH₂O—HCH₂═CHCOO—C(CH₃)₂CH₂O—HCH₂═CHCOO—CH(CH₃) CH(CH₃)O—HCH₂═CHCOO—C(CH₃)(CH₂CH₃)O—HCH₂═CHCOO—(CH₂CH₂O)₂—HCH₂═CHCOO—(CH₂CH₂O)₄—HCH₂═CHCOO—(CH₂CH₂O) s-HCH₂═CHCOO—(CH₂CH₂O)₆—HCH₂═CHCOO—(CH₂CH₂O)₅—CH₃CH₂═CHCOO—(CH₂CH₂O)₉—CH₃CH₂═CHCOO—(CH₂CH₂O)₂₃—CH₃CH₂═CHCOO—(CH₂CH₂O)₉₀—CH₃CH₂═CHCOO—(CH₂CH(CH₃)O)₉—HCH₂═CHCOO—(CH₂CH(CH₃)O)₉—CH₃CH₂═CHCOO—(CH₂CH(CH₃)O)₁₂—CH₃CH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—HCH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃CH₂═CHCOO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉CH₂═CHCOO—(CH₂CH₂O)₂₃—OOC(CH₃) C═CH₂CH₂═CHCOO—(CH₂CH₂O)₂₀—(CH₂CH(CH₃)O) s-CH₂—CH═CH₂CH₂═CHCOO—(CH₂CH₂O)₉—HCH₂═C(CH₃)COO—CH₂CH₂O—HCH₂═C(CH₃)COO—CH₂CH₂CH₂O—HCH₂═C(CH₃)COO—CH₂CH(CH₃)O—HCH₂═C(CH₃)COO—CH(CH₃) CH₂O—HCH₂═C(CH₃)COO—CH₂CH₂CH₂CH₂O—HCH₂═C(CH₃)COO—CH₂CH₂CH(CH₃)O—HCH₂═C(CH₃)COO—CH₂CH(CH₃) CH₂O—HCH₂═C(CH₃)COO—CH(CH₃) CH₂CH₂O—HCH₂═C(CH₃)COO—CH₂CH(CH₂CH₃)O—HCH₂═C(CH₃)COO—CH₂C(CH₃)₂O—HCH₂═C(CH₃)COO—CH(CH₂CH₃) CH₂O—HCH₂═C(CH₃)COO—C(CH₃)₂CH₂O—HCH₂═C(CH₃)COO—CH(CH₃) CH(CH₃)O—HCH₂═C(CH₃)COO—C(CH₃)(CH₂CH₃)O—HCH₂═C(CH₃)COO—(CH₂CH₂O)₂—HCH₂═C(CH₃)COO—(CH₂CH₂O)₄—HCH₂═C(CH₃)COO—(CH₂CH₂O)₅—HCH₂═C(CH₃)COO—(CH₂CH₂O)₆—HCH₂═C(CH₃)COO—(CH₂CH₂O)₉—HCH₂═C(CH₃)COO—(CH₂CH₂O)₅—CH₃CH₂═C(CH₃)COO—(CH₂CH₂O)₉—CH₃CH₂═C(CH₃)COO—(CH₂CH₂O)₂₃—CH₃CH₂═C(CH₃)COO—(CH₂CH₂O)₉₀—CH₃CH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₉—HCH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₉—CH₃CH₂═C(CH₃)COO—(CH₂CH(CH₃)O)₁₂—CH₃CH₂═C(CH₃)COO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—HCH₂═C(CH₃)COO—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃CH₂═C(CH₃)COO—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉CH₂═C(CH₃)COO—(CH₂CH₂O)₂₃—OOC(CH₃) C═CH₂CH₂═C(CH₃)COO—(CH₂CH₂O)₂₀—(CH₂CH(CH₃)O) s-CH₂—CH═CH₂CH₂═CH—C(═O)—NH—CH₂CH₂O—HCH₂═CH—C(═O)—NH—CH₂CH₂CH₂O—HCH₂═CH—C(═O)—NH—CH₂CH(CH₃)O—HCH₂═CH—C(═O)—NH—CH(CH₃) CH₂O—HCH₂═CH—C(═O)—NH—CH₂CH₂CH₂CH₂O—HCH₂═CH—C(═O)—NH—CH₂CH₂CH(CH₃)O—HCH₂═CH—C(═O)—NH—CH₂CH(CH₃) CH₂O—HCH₂═CH—C(═O)—NH—CH(CH₃) CH₂CH₂O—HCH₂═CH—C(═O)—NH—CH₂CH(CH₂CH₃)O—HCH₂═CH—C(═O)—NH—CH₂C(CH₃)₂O—HCH₂═CH—C(═O)—NH—CH(CH₂CH₃) CH₂O—HCH₂═CH—C(═O)—NH—C(CH₃)₂CH₂O—HCH₂═CH—C(═O)—NH—CH(CH₃)CH(CH₃)O—HCH₂═CH—C(═O)—NH—C(CH₃)(CH₂CH₃)O—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₂—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₄—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₆—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₉—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—CH₃CH₂═CH—C(═O)—NH—(CH₂CH₂O)₉—CH₃CH₂═CH—C(═O)—NH—(CH₂CH₂O)₂₃—CH₃CH₂═CH—C(═O)—NH—(CH₂CH₂O)₉₀—CH₃CH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₉—HCH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₉—CH₃CH₂═CH—C(═O)—NH—(CH₂CH(CH₃)O)₁₂—CH₃CH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—HCH₂═CH—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃CH₂═CH—C(═O)—NH—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉CH₂═C(CH₃)—C(═O)—NH—CH₂CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₃)O—HCH₂═C(CH₃)—C(═O)—NH—CH(CH₃) CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH₂CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH₂CH(CH₃)O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₃)CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH(CH₃)CH₂CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH₂CH(CH₂CH₃)O—HCH₂═C(CH₃)—C(═O)—NH—CH₂C(CH₃)₂O—HCH₂═C(CH₃)—C(═O)—NH—CH(CH₂CH₃) CH₂O—HCH₂═C(CH₃)—C(═O)—NH—C(CH₃)₂CH₂O—HCH₂═C(CH₃)—C(═O)—NH—CH(CH₃)CH(CH₃)O—HCH₂═C(CH₃)—C(═O)—NH—C(CH₃)(CH₂CH₃)O—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₂—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₄—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₆—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₂₃—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₉₀—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₉—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₉—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH(CH₃)O)₁₂—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₂—HCH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₅—(CH₂CH(CH₃)O)₃—CH₃CH₂═C(CH₃)—C(═O)—NH—(CH₂CH₂O)₈—(CH₂CH(CH₃)O)₆—CH₂CH(C₂H₅) C₄H₉

The monomer (b) is preferably acrylate or acrylamide in which X² is ahydrogen atom. Particularly, hydroxyethyl acrylate, hydroxypropylacrylate, hydroxybutyl acrylate, or hydroxyethyl acrylamide ispreferable.

(c) Monomer Having Ion Donating Group

The monomer having an ion donating group (c) is a monomer different fromthe monomer (a) and the monomer (b). The monomer (c) is preferably amonomer having an olefinic carbon-carbon double bond and an ion donatinggroup. The ion donating group is an anion donating group and/or a cationdonating group.

Examples of the monomer having an anion donating group include monomershaving a carboxyl group, a sulfonic acid group, or a phosphoric acidgroup. Specific examples of the monomer having an anion donating groupinclude (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid,itaconic acid, citraconic acid, vinyl sulfonic acid, (meth)allylsulfonicacid, styrenesulfonic acid, phosphoric acid (meth)acrylate,vinylbenzenesulfonic acid, acrylamide tert-butyl sulfonic acid, andsalts thereof.

Examples of salts of the anion donating group include alkali metalsalts, alkaline earth metal salts, and ammonium salts, such as a methylammonium salt, an ethanol ammonium salt, and a triethanol ammonium salt.

In the monomer having a cation donating group, examples of the cationdonating group include an amino group and preferably a tertiary aminogroup and a quaternary amino group. In the tertiary amino group, twogroups bonded to the nitrogen atom are the same or different and arepreferably an aliphatic group having 1 to 5 carbon atoms (particularlyan alkyl group), an aromatic group having 6 to 20 carbon atoms (an arylgroup), or an araliphatic group having 7 to 25 carbon atoms(particularly an aralkyl group such as a benzyl group (C₆H₅—CH₂—)). Inthe quaternary amino group, three groups bonded to the nitrogen atom arethe same or different and are preferably an aliphatic group having 1 to5 carbon atoms (particularly an alkyl group), an aromatic group having 6to 20 carbon atoms (an aryl group), or an araliphatic group having 7 to25 carbon atoms (particularly an aralkyl group such as a benzyl group(C₆H₅—CH₂—)). In the tertiary and quaternary amino groups, the remainingone group bonded to the nitrogen atom may have a carbon-carbon doublebond. The cation donating group may be in the form of a salt.

A cation donating group which is a salt is a salt formed with an acid(an organic acid or an inorganic acid). Organic acids such as carboxylicacids having 1 to 20 carbon atoms (particularly, monocarboxylic acidssuch as acetic acid, propionic acid, butyric acid, and stearic acid) arepreferable. Dimethylaminoethyl (meth)acrylate, diethylaminoethyl(meth)acrylate, and salts thereof are preferable.

Specific examples of the monomer having a cation donating group are asfollows.

CH₂═CHCOO—CH₂CH₂—N(CH₃)₂ and salts thereof (such as acetate)CH₂═CHCOO—CH₂CH₂—N(CH₂CH₃)₂ and salts thereof (such as acetate)CH₂═C(CH₃)COO—CH₂CH₂—N(CH₃)₂ and salts thereof (such as acetate)CH₂═C(CH₃)COO—CH₂CH₂—N(CH₂CH₃)₂ and salts thereof (such as acetate)CH₂═CHC(O) N(H)—CH₂CH₂CH₂—N(CH₃)₂ and salts thereof (such as acetate)CH₂═CHCOO—CH₂CH₂—N(—CH₃) (—CH₂—C₆H₅) and salts thereof (such as acetate)CH₂═C(CH₃)COO—CH₂CH₂—N(—CH₂CH₃) (—CH₂—C₆H₅) and salts thereof (such asacetate)CH₂═CHCOO—CH₂CH₂—N⁺(CH₃)₃Cl⁻CH₂═CHCOO—CH₂CH₂—N⁺(—CH₃)₂ (—CH₂—C₆H₅) Cl⁻CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃Cl⁻CH₂═CHCOO—CH₂CH(OH) CH₂—N⁺(CH₃)₃Cl⁻CH₂═C(CH₃)COO—CH₂CH(OH) CH₂—N⁺(CH₃)₃Cl⁻CH₂═C(CH₃)COO—CH₂CH(OH) CH₂—N⁺(—CH₂CH₃)₂ (—CH₂—C₆H₅) Cl⁻CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃Br⁻CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃I⁻CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃)₃O⁻SO₃CH₃CH₂═C(CH₃)COO—CH₂CH₂—N⁺(CH₃) (—CH₂—C₆H₅)₂Br⁻

The monomer having an ion donating group (c) is preferably methacrylicacid, acrylic acid, and dimethylaminoethyl methacrylate, and morepreferably methacrylic acid and dimethylaminoethyl methacrylate.

(d) Another Monomer

Another monomer (d) is a monomer different from the monomers (a), (b),and (c). Examples of the other monomer include ethylene, vinyl acetate,vinyl chloride, vinyl fluoride, halogenated vinyl styrene,α-methylstyrene, p-methylstyrene, polyoxyalkylene mono(meth)acrylate,(meth)acrylamide, diacetone (meth)acrylamide, methylollated(meth)acrylamide, N-methylol (meth)acrylamide, alkyl vinyl ether,halogenated alkyl vinyl ether, alkyl vinyl ketone, butadiene, isoprene,chloroprene, glycidyl (meth)acrylate, aziridinyl (meth)acrylate, benzyl(meth)acrylate, isocyanate ethyl (meth)acrylate, cyclohexyl(meth)acrylate, isobornyl (meth)acrylate, short-chain alkyl(meth)acrylate, maleic anhydride, (meth)acrylate having apolydimethylsiloxane group, and N-vinylcarbazole.

The amount of the repeating unit formed from the monomer (a) may be 30to 95% by weight, preferably 40 to 88% by weight, and more preferably 50to 85% by weight, based on the fluorine-free polymer (particularly, anacrylic polymer).

The amount of the repeating unit formed from the monomer (b) may be 5 to70% by weight, preferably 8 to 50% by weight, and more preferably 10 to40% by weight, based on the fluorine-free polymer.

The amount of the repeating unit formed from the monomer (c) may be 0.1to 30% by weight, preferably 0.5 to 20% by weight, and more preferably 1to 15% by weight, based on the fluorine-free polymer.

The amount of the repeating unit formed from the monomer (d) may be 0 to20% by weight, such as 1 to 15% by weight, particularly 2 to 10% byweight, based on the fluorine-free copolymer.

The weight-average molecular weight of the fluorine-free polymer may be1,000 to 10,000,000, preferably 5,000 to 8,000,000, and more preferably10,000 to 4,000,000. The weight-average molecular weight is a valueobtained in terms of polystyrene by gel permeation chromatography.

Herein, “(meth)acryl” means acryl or methacryl. For example,“(meth)acrylate” means acrylate or methacrylate.

From the viewpoint of oil resistance, the fluorine-free polymer(particularly, an acrylic polymer) is preferably a random copolymerrather than a block copolymer.

Polymerization for the fluorine-free polymer is not limited, and variouspolymerization methods can be selected, such as bulk polymerization,solution polymerization, emulsion polymerization, and radiationpolymerization. For example, in general, solution polymerizationinvolving an organic solvent, and emulsion polymerization involvingwater or involving an organic solvent and water in combination, areselected. The fluorine-free copolymer after polymerization is dilutedwith water to be emulsified in water and thus formed into a treatmentliquid.

Herein, it is preferable that after polymerization (for example,solution polymerization or emulsion polymerization, preferably solutionpolymerization), water is added, and then the solvent is removed todisperse the polymer in water. An emulsifier does not need to be added,and a self-dispersive product can be produced.

Examples of organic solvents include ketones such as acetone and methylethyl ketone, esters such as ethyl acetate and methyl acetate, glycolssuch as propylene glycol, dipropylene glycol monomethyl ether,N-methyl-2-pyrrolidone (NMP), dipropylene glycol, tripropylene glycol,and low molecular weight polyethylene glycol, and alcohols such as ethylalcohol and isopropanol.

For example, peroxide, an azo compound, or a persulfate compound can beused as a polymerization initiator. The polymerization initiator is, ingeneral, water-soluble and/or oil-soluble.

Specific examples of the oil-soluble polymerization initiator preferablyinclude 2,2′-azobis(2-methylpropionitrile),2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile),1,1′-azobis(cyclohexan-1-carbonitrile), dimethyl2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-isobutyronitrile),benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, cumenehydroperoxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate,and t-butyl perpivalate.

Specific examples of the water-soluble polymerization initiatorpreferably include 2,2′-azobisisobutylamidine dihydrochloride,2,2′-azobis(2-methylpropionamidine) hydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane] sulfate hydrate,2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] hydrochloride,potassium persulfate, barium persulfate, ammonium persulfate, andhydrogen peroxide.

The polymerization initiator is used in the range of 0.01 to 5 parts byweight, based on 100 parts by weight of the monomers.

In order to regulate the molecular weight, a chain transfer agent suchas a mercapto group-containing compound may be used, and specificexamples thereof include 2-mercaptoethanol, thiopropionic acid, andalkyl mercaptan. The mercapto group-containing compound is used in therange of 10 parts by weight or less, or 0.01 to 5 parts by weight, basedon 100 parts by weight of the monomers.

Specifically, the fluorine-free polymer can be produced as follows.

In solution polymerization, a method is employed that involvesdissolving the monomers in an organic solvent, performing nitrogenpurge, then adding a polymerization initiator, and heating and stirringthe mixture, for example, in the range of 40 to 120° C. for 1 to 10hours. The polymerization initiator may be, in general, an oil-solublepolymerization initiator.

The organic solvent is inert to and dissolves the monomers, and examplesinclude ketones such as acetone and methyl ethyl ketone, esters such asethyl acetate and methyl acetate, glycols such as propylene glycol,dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone (NMP),dipropylene glycol, tripropylene glycol, and low molecular weightpolyethylene glycol, alcohols such as ethyl alcohol and isopropanol, andhydrocarbon solvents such as n-heptane, n-hexane, n-octane, cyclohexane,methylcyclohexane, cyclopentane, methylcyclopentane, methylpentane,2-ethylpentane, isoparaffin hydrocarbon, liquid paraffin, decane,undecane, dodecane, mineral spirit, mineral turpen, and naphtha.Preferable examples of the solvent include acetone, chloroform, HCHC225, isopropyl alcohol, pentane, hexane, heptane, octane, cyclohexane,benzene, toluene, xylene, petroleum ether, tetrahydrofuran, 1,4-dioxane,methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butylacetate, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane,trichloroethylene, perchloroethylene, tetrachlorodifluoroethane,trichlorotrifluoroethane, N-methyl-2-pyrrolidone (NMP), and dipropyleneglycol monomethyl ether (DPM). The organic solvent is used in the rangeof 50 to 2,000 parts by weight, such as 50 to 1,000 parts by weight,based on total 100 parts by weight of the monomers.

In emulsion polymerization, a method is employed that involvesemulsifying the monomers in water in the presence of an emulsifier,performing nitrogen purge, then adding a polymerization initiator, andstirring the mixture in the range of 40 to 80° C. for 1 to 10 hours forpolymerization. As the polymerization initiator, a water-solublepolymerization initiator such as 2,2′-azobisisobutylamidinedihydrochloride, 2,2′-azobis(2-methylpropionamidine) hydrochloride.2,2′-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride,2,2′-azobis[2-(2-imidazolin-2-yl)propane] sulfate hydrate,2,2′-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] hydrochloride,potassium persulfate, barium persulfate, ammonium persulfate, orhydrogen peroxide; or an oil-soluble polymerization initiator such as2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile),1,1′-azobis(cyclohexan-1-carbonitrile), dimethyl2,2′-azobis(2-methylpropionate), 2,2′-azobis(2-isobutyronitrile),benzoyl peroxide, di-tert-butyl peroxide, lauryl peroxide, cumenehydroperoxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, ort-butyl perpivalate is used. The polymerization initiator is used in therange of 0.01 to 10 parts by weight, based on 100 parts by weight of themonomers.

In order to obtain a water dispersion of the polymer, that has excellentstability when being left to stand, it is desirable that the monomersare formed into particles in water by using an emulsifying apparatuscapable of applying strong crushing energy such as a high-pressurehomogenizer or an ultrasonic homogenizer, and polymerized by using anoil-soluble polymerization initiator. Various anionic, cationic, ornonionic emulsifiers can be used as emulsifiers, and are used in therange of 0.5 to 20 parts by weight, based on 100 parts by weight of themonomers. An anionic and/or nonionic and/or cationic emulsifier ispreferably used. When the monomers are not completely compatible, acompatibilizer such as a water-soluble organic solvent or a lowmolecular weight monomer that causes the monomers to be sufficientlycompatible is preferably added. By adding a compatibilizer,emulsifiability and copolymerizability can be increased.

Examples of the water-soluble organic solvent include acetone, propyleneglycol, dipropylene glycol monomethyl ether (DPM), dipropylene glycol,tripropylene glycol, ethanol, N-methyl-2-pyrrolidone (NMP),3-methoxy-3-methyl-1-butanol, or isoprene glycol, and the water-solubleorganic solvent may be used in the range of 1 to 50 parts by weight,such as 10 to 40 parts by weight, based on 100 parts by weight of water.By adding NMP or DPM or 3-methoxy-3-methyl-1-butanol or isoprene glycol(a preferable amount is, for example, 1 to 20% by weight, andparticularly 3 to 10% by weight, based on the composition), thestability of the composition (particularly, the emulsion) is increased.Examples of the low molecular weight monomer include methylmethacrylate, glycidyl methacrylate, and 2,2,2-trifluoroethylmethacrylate, and the low molecular weight monomer may be used in therange of 1 to 50 parts by weight, such as 10 to 40 parts by weight,based on total 100 parts by weight of the monomers.

The amount of the fluorine-free polymer (1) is 0.1 to 99% by weight,based on the total weight of the fluorine-free polymer (1) and theparticles (2). The lower limit of the amount of the fluorine-freepolymer (1) may be 1% by weight, such as 5% by weight, particularly 10%by weight, and especially 20% by weight or 30% by weight. The upperlimit of the amount of the fluorine-free polymer (1) may be 90% byweight, such as 70% by weight, particularly 60% by weight, andespecially 50% by weight or 40% by weight.

(2) Particle

The particles (2) comprise at least one type of inorganic particles ororganic particles. The particles (2) preferably comprise organicparticles. The particles (2) more preferably comprise both inorganicparticles and organic particles.

The inorganic particles are particles made of inorganic materials.Examples of the inorganic materials constituting the inorganic particlesinclude calcium carbonate, talc, kaolin (and calcined kaolin), clay (andcalcined clay), mica, aluminum hydroxide, barium sulfate, calciumsilicate, calcium sulfate, silica, zinc carbonate, zinc oxide, titaniumoxide, bentonite, and white carbon. Calcium carbonate, silica, andcalcined clay are preferable. Calcium carbonate is particularlypreferable.

The organic particles are particles made of organic materials. Examplesof the organic materials constituting the organic particles includepolysaccharides and thermoplastic resins (such as polyvinyl alcohol,polyolefin, polystyrene). The organic particles (such as particles ofpolysaccharides and particles of thermoplastic resins) may be modified(for example, cation-modified or anion-modified). Polysaccharides arepreferable.

The polysaccharides are biopolymers synthesized in biological systems bythe condensation and polymerization of various monosaccharides,including those that have been chemically modified (denatured). Examplesof polysaccharides include starch, cellulose, modified cellulose,amylose, amylopectin, pullulan, curdlan, xanthan, chitin, and chitosan.Examples of modified cellulose include hydroxymethyl cellulose,hydroxyethyl cellulose, and carboxymethyl cellulose.

The polysaccharides are preferably starch. Starch particles haveexcellent dispersibility in the pulp slurry. The starch may be anundenatured starch. Examples of the starches include rice flour starch,wheat starch, corn starch, potato starch, tapioca starch, sweet potatostarch, adzuki bean starch, mung bean starch, kudzu starch, and dogtoothviolet starch. The starch may be those that have been denatured, such asenzymatic denaturation, thermochemical denaturation, acetateesterification, phosphate esterification, carboxy etherification,hydroxy etherification, and cationic denaturation. Since it gives highair permeability and high oil resistance, the starch is preferablyamphoterized starch (starch having a cation group and an anion group) orcationized starch (starch having a cation group). A combination ofamphoterized starch and cationized starch (at a preferred weight ratioof 0.1:9.9 to 4:6 or 0.5:9.5 to 2:8) is preferable since it alsoincreases water resistance.

In the particles (2), the cation group (particularly, the cation groupin the amphoterized starch or the cationized starch) may be a cationgroup similar to the cation group in the monomer having the ion donatinggroup (c), such as an amino group, and the anion group (particularly,the anion group in the amphoterized starch) may be an anion groupsimilar to the anion group in the monomer having the ion donating group(c), such as a carboxyl group, a sulfonic acid group, and a phosphoricacid group.

The particles (2) may have a powdery, granular, fibrous, flaky, or alike form.

The particles (inorganic particles and organic particles) are preferablyinsoluble in water at 40° C. Insoluble in water means that thesolubility in 100 g of water at 40° C. is 1 g or less, such as 0.5 g orless.

The average particle size of the particles may be 0.01 to 100 μm, suchas 0.1 to 50 μm, particularly 1.0 to 20 μm.

The average particle size can be measured by a laser diffractionparticle size distribution measurement apparatus (applying lightscattering theory) using a water dispersion of the particles.

The dissolution temperature of organic particles in water is preferablyabout 55° C. or more (for example, 60° C. to 100° C.). The “dissolutiontemperature” means the highest temperature at which the appearance ofthe liquid changes from cloudy to transparent after adding 5 parts byweight of organic particles based on 100 parts by weight of watermaintained at the target temperature with stirring by visual observationunder atmospheric pressure (the liquid might be cloudy at the time ofaddition), and maintaining the liquid at the temperature for 30 minuteswith continuous stirring.

Examples of such organic particles that can be dissolved in water areundenatured starch, denatured starch (such as cationized starch), locustbean gum, carboxymethyl cellulose, and polyvinyl alcohol.

The organic particles may be ionic or nonionic. If the pulp is ionic,the organic particles are preferably ionic, more specifically anionic,cationic, or amphoteric organic particles, so that they can be easilyanchored to the pulp in the pulp slurry and the product. Particularly,if the pulp is ionic, it is preferable to use organic particles havingthe opposite ionic part to the pulp, so that the organic particles canbe effectively anchored to the pulp (preferably together with anoil-resistant agent) and the gas barrier properties of the finallyobtained molded pulp container can be enhanced. Pulps are usuallyanionic, and for such pulps, it is preferable that the organic particleshave a cationic moiety, or more particularly are cationized oramphoterized.

Organic particles having cation moieties include cationized starch,amphoteric starch, and cation-modified polyvinyl alcohol.

The amount of the particles (2) is 1 to 99.9% by weight, based on thetotal weight of the fluorine-free polymer (1) and the particles (2). Thelower limit of the amount of the particles (2) may be 10% by weight,such as 30% by weight or 40% by weight, particularly 50% by weight or60% by weight, and especially 65% by weight or 70% by weight. The upperlimit of the amount of the particles (2) may be 99% by weight or 98% byweight, such as 97% by weight or 95% by weight, particularly 90% byweight, and especially 80% by weight or 70% by weight. Alternatively,the amount of the particles (2) may be 60 to 99% by weight, such as 65to 98% by weight, particularly 70 to 97% by weight, based on the totalweight of the fluorine-free polymer (1) and the particles (2).

(3) Another Component

The oil-resistant agent may comprise another component (3) other thanthe fluorine-free polymer (1) and the particles (2). Examples of theother component (3) include an aqueous medium and an emulsifier.

The aqueous medium is water or a mixture of water and an organic solvent(an organic solvent miscible with water). The amount of the aqueousmedium may be 50% by weight to 99.99% by weight, based on the totalamount of the fluorine-free polymer (1) (and the particles (2), ifnecessary) and the aqueous medium.

The amount of the emulsifier may be 0 to 30 parts by weight, such as 0.1to 10 parts by weight, based on 100 parts by weight of the fluorine-freepolymer (1).

[Oil-Resistant Agent]

The oil-resistant agent may be in the form of a solution, an emulsion,or an aerosol. The oil-resistant agent may comprise the fluorine-freepolymer (1) and a liquid medium. The liquid medium is, for example, anorganic solvent and/or water, and preferably an aqueous medium. Theaqueous medium is water or a mixture of water and an organic solvent(such as polypropylene glycol and/or a derivative thereof).

In the case of a dispersion (emulsion) form, the fluorine-free polymeris a water dispersion type which is dispersed in an aqueous medium, andthe fluorine-free polymer (1) may be self-emulsified, dispersed in theaqueous medium in the form of a neutralized salt, or emulsified using anemulsifier.

The particles (2) may be used in the form of solid or dispersed in aliquid medium. The fluorine-free polymer (1) and the particles (2) maybe dispersed in the same liquid medium or may be dispersed in differentliquid media. In the oil-resistant agent, the concentration of thefluorine-free polymer may be, for example, 0.01 to 50% by weight. Theoil-resistant agent may either comprise or not comprise an emulsifier,but it is preferable not to comprise an emulsifier.

The oil-resistant agent can be used to treat a paper substrate. The“treatment” means that the oil-resistant agent is applied to interiorand/or exterior of paper.

The oil-resistant agent can be applied to the substrate by aconventionally known method. The oil-resistant agent is mainly presentinside the paper through internal treatment.

Examples of the paper substrate to be treated include paper, a containermade of paper, and a molded article made of paper (for example, moldedpulp).

The fluorine-free polymer favorably adheres to the paper substrate.

The oil-resistant agent should be used such that the amount offluorine-free polymer (1) and the particles (2) is 0.01 to 75 parts byweight, such as 0.1 to 60 parts by weight, based on 100 parts by weightof pulp solids.

[Papermaking]

Paper can be produced by a conventionally known papermaking method. Aninternal treatment method in which the oil-resistant agent is added to apulp slurry before papermaking, or an external treatment method in whichthe oil-resistant agent is applied to paper after papermaking, can beused. The method of treatment with the oil-resistant agent in thepresent disclosure is preferably an internal treatment method. Even ifthe oil-resistant agent of the present disclosure is used in theinternal treatment, no new equipment is required.

In the internal treatment method, paper treated by the oil-resistantagent may be produced by mixing the oil-resistant agent with pulp slurryand paper making. The paper treated by the oil-resistant agent isoil-resistant paper having oil resistance. The oil-resistant paper canbe thin or thick, or molded pulp.

Paper thus treated, after rough drying at room temperature or hightemperature, is optionally subjected to a heat treatment that can have atemperature range of up to 300° C., such as up to 200° C., particularly80° C. to 180° C., depending on the properties of the paper, and thusshows excellent oil resistance and water resistance.

The present disclosure can be used in gypsum board base paper, coatedbase paper, wood containing paper, commonly used liner and corrugatingmedium, neutral machine glazed paper, neutral liner, rustproof liner andmetal laminated paper, kraft paper, and the like. The present disclosurecan also be used in neutral printing writing paper, neutral coated basepaper, neutral PPC paper, neutral heat sensitive paper, neutral pressuresensitive base paper, neutral inkjet paper, and neutral communicationpaper.

A pulp (pulp raw material) may be any of bleached or unbleached chemicalpulp such as kraft pulp or sulfite pulp, bleached or unbleached highyield pulp such as ground pulp, mechanical pulp, or thermomechanicalpulp, waste paper pulp such as waste newspaper, waste magazine, wastecorrugated cardboard, or waste deinked paper, and non-wood pulp such asbagasse pulp, kenaf pulp, or bamboo pulp. The pulp raw material may be acombination of one or more of these. A mixture of the above pulp rawmaterial and one or more of synthetic fiber of asbestos, polyamide,polyimide, polyester, polyolefin, or the like can be used as well.

In the internal treatment, a pulp slurry having a pulp concentration of0.5 to 5.0% by weight (such as 2.5 to 4.0% by weight) is preferablyformed into paper. An additive (such as a sizing agent, a paperstrengthening agent, a flocculant, a retention aid, or a coagulant) andthe fluorine-free polymer can be added to the pulp slurry. Since thepulp is generally anionic, at least one of the additive and thefluorine-free polymer is preferably cationic or amphoteric such that theadditive and the fluorine-free polymer are favorably anchored to paper.A combination of a cationic or amphoteric additive and an anionicfluorine-free polymer, a combination of an anionic additive and acationic or amphoteric fluorine-free polymer, and a combination of acationic or amphoteric additive and fluorine-free polymer are preferablyused.

Other components (additives) may be used in addition to theoil-resistant agent. Examples of the other components are cationiccoagulants, water-resistant agents, paper strength additives,flocculants, fixing agents, and yield improvers.

Cationic coagulants, paper strength additives, flocculants, fixingagents, and yield improvers can be polymers or inorganic materials whichare cationic or amphoteric. The cationic coagulants, paper strengthadditives, flocculants, fixing agents, and yield improvers caneffectively anchor the oil-resistant agent consisting of thefluorine-free polymer (1) and the particles (2) to the pulp, which isgenerally anionic, and the gas barrier properties and/or waterresistance and oil resistance of the finally obtained molded pulpcontainer can be enhanced.

Examples of cationic coagulants, paper strength additives, flocculants,fixing agents, and yield improvers include a polyamine epichlorohydrinresin, a polyamide epichlorohydrin resin, cationic polyacrylamide (anacrylamide-allylamine copolymer, an acrylamide-dimethylaminoethyl(meth)acrylate copolymer, an acrylamide-diethylaminoethyl (meth)acrylatecopolymer, an acrylamide-quaternized dimethylaminoethyl (meth)acrylatecopolymer, an acrylamide-quaternized diethylaminoethyl (meth)acrylatecopolymer, or the like), polydiallyldimethylammonium chloride,polyallylamine, polyvinylamine, polyethyleneimine, anN-vinylformamide-vinylamine copolymer, a melamine resin, a polyamideepoxy resin, sulfate band, PAC (polyaluminum chloride), aluminumchloride, and ferric chloride. Particularly,polyamidepolyamine-epichlorohydrin (PAE), polydiallyldimethylammoniumchloride (poly-DADMAC), polyacrylamide (PAM), and the like can be used.

A water-resistant agent may be used in addition to the oil-resistantagent. In the present disclosure, the “water-resistant agent” refers toa component that, when added to the pulp slurry, is capable ofincreasing the water resistance of a molded pulp product as compared tothe case where it is not added (provided that the above-describedoil-resistant agent is excluded). Due to the water-resistant agent, thewater resistance of the finally obtained molded pulp container can beincreased. The above-described cationic coagulant is generally incapableof increasing water resistance by itself and can be understood as beingdifferent from the water-resistant agent.

A sizing agent or the like used in ordinary papermaking is usable as awater-resistant agent. Examples of the water-resistant agent includecationic sizing agents, anionic sizing agents, and rosin-based sizingagents (such as acidic rosin-based sizing agents or neutral rosin-basedsizing agents), and cationic sizing agents are preferable. Particularly,a styrene-containing polymer such as a styrene-(meth)acrylate copolymer,an alkenyl succinic anhydride, and an alkyl ketene dimer are preferable.

If necessary, a dye, a fluorescent dye, a slime control agent, anantislip agent, an antifoaming agent, and a pitch control agent whichare usually used as paper making chemicals in paper treatment agents mayalso be used.

Paper is preferably a molded pulp product. The molded pulp product canbe produced by a producing method comprising: preparing a formulatedpulp slurry by adding an oil-resistant agent to a slurry in which pulpis dispersed in an aqueous medium, making a molded pulp intermediate,followed by dehydrating and then at least drying to obtain a molded pulpproduct.

The preparation of the formulated pulp slurry is preferably performedsuch that the organic particles remain in a solid state. For example,the formulated pulp slurry is prepared at a temperature lower than, forexample, a temperature at least 5° C. lower than the dissolutiontemperature of the organic particles. In the formulated pulp slurryprepared, the organic particles remain in a solid state (powdery,granular, fibrous, flaky, or the like depending on the organic particlesused as a raw material), and for example, when starch powder is used asa raw material, the starch powder may remain dispersed in an aqueousmedium.

The oil-resistant agent and the organic particles, and optionally thecationic coagulant and/or the water-resistant agent or the like may beadded to the pulp slurry in any order as long as the organic particlesremain in a solid state.

The content of each component in the formulated pulp slurry (based onall components) can be suitably selected so as to attain a high freenesssuitable for papermaking and dehydrating and the physical propertiesdesired of a molded pulp product, and, for example, can be as follows.

Aqueous medium: 89.5 to 99.89% by weight, particularly 94.5 to 99.69% byweight

Pulp: 0.1 to 5% by weight, particularly 0.3 to 2.5% by weight

Oil-resistant agent (solids): 0.00001 to 1% by weight, particularly0.0001 to 0.5% by weight

Cationic coagulant (solids): 0 to 1% by weight, particularly 0 to 0.5%by weight (when added, for example, 0.00005% by weight or more)

Water-resistant agent (solids): 0 to 1% by weight, particularly 0 to0.5% by weight (when added, for example, 0.00005% by weight or more)

When each component is in the form of, for example, a dispersion, theabove content indicates the solid content (based on all components) ofeach component in the formulated pulp slurry.

From another viewpoint, the content of each of the pulp and theoil-resistant agent based on the aqueous medium in the formulated pulpslurry can be suitably selected so as to attain a high freeness suitablefor papermaking and dehydrating, and for example, can be as follows.

Pulp: 0.1 to 5.58% by weight, particularly 0.3 to 2.64% by weight

Oil-resistant agent (solids): 0.001 to 2.79% by weight, particularly0.005 to 1.05% by weight

When the organic particles are dissolved in the aqueous medium (or whenan aqueous solution in which the organic particles such as starch aredissolved in advance in the aqueous medium is added to a pulp slurry),the resulting aqueous composition has a reduced freeness. On the otherhand, in the formulated pulp slurry, the organic particles remain in asolid state without being dissolved in the aqueous medium, andtherefore, as compared to the case where the organic particles aredissolved in the aqueous medium, a larger amount of the organicparticles can be added while maintaining the high freeness of theformulated pulp slurry.

Next, the formulated pulp slurry prepared above is made to form a moldedpulp intermediate, the molded pulp intermediate is dehydrated and thenat least dried to obtain a molded pulp product.

Papermaking, dehydrating, and drying can be performed according toconventionally known methods concerning molded pulp.

For example, by straining the formulated pulp slurry to dehydrate it(for example, by suction and/or pressure reduction) using a mold whichhas a desired shape and which is provided with numerous holes (and thatmay be equipped with a filter as necessary), the aqueous medium can beat least partially removed from the formulated pulp slurry, and a moldedpulp intermediate having a shape that corresponds to the mold can beobtained.

The process from the preparation to the dehydration of the formulatedpulp slurry is performed, with the organic particles remaining in asolid state. For example, after preparation, dehydrating is performed ata temperature lower than, such as a temperature at least 5° C. lowerthan the dissolution temperature of the organic particles. As forpapermaking and dehydrating, the aqueous medium is removed from theformulated pulp slurry through a mold (and optionally a filter), andtherefore, an excessively lowered freeness of the formulated pulp slurrydue to dissolution of the organic particles makes it substantiallyimpossible to perform papermaking and dehydrating and is thus notpreferable. On the other hand, with the organic particles remaining in asolid state, the freeness of the formulated pulp slurry is not lowered,and papermaking and dehydrating can be appropriately performed.

After dehydrating, in the resulting molded pulp intermediate, theorganic particles remain in a solid state (powdery, granular, fibrous,flaky, or the like depending on the organic particles used as rawmaterials) and, for example, when starch powder is used as a rawmaterial, the starch powder may be dispersed in the pulp.

Drying does not need to be performed such that the organic particlesremain in a solid state, and can be performed at a temperature at whichthe remaining aqueous medium can be effectively removed (if applicable,it can be a temperature equal to or higher than the dissolutiontemperature of the organic particles), for example, 90 to 250° C.,particularly 100 to 200° C. The drying time is not limited, and can beselected such that the aqueous medium remaining in the molded pulpintermediate is substantially removed. The drying atmosphere is notlimited, and may be conveniently an ambient atmosphere (air under normalpressure).

During and/or after drying, other steps which are conventionally knownconcerning molded pulp, for example, press molding (including heatpressing), may be performed if necessary.

During drying and/or press molding, causing the organic particles to atleast partially dissolve makes it possible to obtain even higher gasbarrier properties. The organic particles do not need to dissolveentirely, and the organic particles may partially remain in a solidstate.

Thus, a molded pulp product can be produced. This molded pulp productcomprises a pulp, an oil-resistant agent, and can achieve high gasbarrier properties and excellent water resistance and oil resistance.

In the molded pulp product of the present disclosure, the content of theorganic particles based on the pulp is 0.0001 to 75% by weight, such as0.1 to 60% by weight, particularly 2 to 50% by weight.

When a molded pulp product is obtained by adding an aqueous solution inwhich organic particles such as starch are dissolved in advance in anaqueous medium to a pulp slurry to increase strength, a sufficientstrength improving effect can be obtained even when the content oforganic particles based on the pulp is low, and it was thus not requiredto increase the content of the organic particles based on the pulp.

In the present disclosure, the content of the organic particles based onthe pulp is preferably high, and the lower limit of the content of theorganic particles based on the pulp may be 3% by weight or 5% by weight,such as 8% by weight or 10% by weight, particularly 15% by weight. Theupper limit of the content of the organic particles based on the pulpmay be 60% by weight, such as 50% by weight or 40% by weight,particularly 30% by weight or 20% by weight. The content of the organicparticles based on the pulp may be 3 to 70% by weight or 5 to 60% byweight, such as 8 to 50% by weight or 8 to 40% by weight. In otherwords, the content of the organic particles may be 3 to 70 parts byweight or 5 to 60 parts by weight, such as 8 to 50 parts by weight or 8to 40 parts by weight, based on the 100 parts by weight of the pulp.With such a high content of the organic particles, it is possible to notonly obtain high gas barrier properties but also further increase waterresistance and oil resistance.

In the molded pulp product, the organic particles may be derived fromstarch powder dispersed in the aqueous medium (in the formulated pulpslurry).

The proportions of the pulp, the organic particles, the oil-resistantagent, and optionally the cationic coagulant and/or the water-resistantagent contained in the molded pulp product can be consideredsubstantially the same as the solid contents of these components used asraw materials (usually, the aqueous medium and, if present, other liquidmedia can be removed by drying and press molding, but the solids canremain without being removed or decomposed).

In the molded pulp product, the content of each component (a componentthat can remain in the molded pulp product) based on the pulp (solids)can be suitably selected according to the physical properties desired ofthe molded pulp product, and, for example, can be as follows.

Oil-resistant agent (solids): 0.01 to 50% by weight or 0.01 to 20% byweight, particularly 0.05 to 10% by weight

Cationic coagulant (solids): 0 to 20% by weight, particularly 0 to 10%by weight (if present, such as 0.001% by weight or more)

water-resistant agent (solids): 0 to 20% by weight, particularly 0 to10% by weight (if present, such as 0.001% by weight or more)

The oil-resistant agent are internally added to the molded pulp product(they are added to a pulp slurry, and the molded pulp product isproduced by a pulp molding method). Accordingly, after the molded pulpproduct is used, the entirety of the product can be crushed to bring itback to the original raw materials, and is thus suitable for recycleuse. Furthermore, it is possible to utilize the intrinsicbiodegradability of the pulp, the molded pulp product can extremelyreduce and preferably can substantially eliminate the environmentalburden. Also, with the molded pulp product, the texture of the pulp canbe maintained on the front side of the product, and the appearance isnot impaired unlike when the front side is laminated with a plastic filmand becomes glossy.

The molded pulp product can be suitably used as food containers(including trays and the like), for example, storage containers forfrozen food and chilled food.

Since the molded pulp product of the present disclosure has excellentwater resistance and oil resistance, moisture and oil derived from fooddo not impregnate the molded pulp product (a container), and it is thuspossible to prevent deterioration of container strength resulting fromimpregnation with water and oil and prevent staining of the tablesurface or the like facing the bottom surface of the container withmoisture and oil permeated through the container. Also, the molded pulpproduct of the present disclosure has high gas barrier properties andunlikely allows gas and water vapor to permeate, and thus, whenaccommodating hot and wet food or when heated in a microwave with foodbeing accommodated therein, it is possible to prevent the problem thatgas and water vapor derived from food permeate through the container andleak to the outside and, particularly, condense on the table surface orthe like facing the bottom surface of the container. Further, the moldedpulp product of the present disclosure has high gas barrier propertiesand unlikely allow gas and water vapor (or moisture) to permeate, andthus, when refrigerating accommodated food, evaporation of water fromfood and exposure of food to oxygen can be effectively reduced, freezerburn resulting therefrom can be effectively prevented, and the flavor offood can be maintained for a long period of time.

Embodiments have been described above, but it will be understood thatvarious changes to form and detail can be made without departing fromthe spirit and scope of the claims.

EXAMPLES

Next, the present disclosure will now be described in detail by way ofExamples, Comparative Examples, and Test Examples. However, thedescription of these does not limit the present disclosure.

Below, a part, %, and a ratio indicate a part by weight, % by weight,and a weight ratio, respectively, unless otherwise specified.

The test methods used below are as follows.

[High-Temperature Oil Resistance]

First, 100 ml of an evaluation liquid (corn oil) at 90° C. was pouredinto a molded pulp product molded into a container shape, the moldedpulp product was left to stand still for 30 minutes, then the evaluationliquid was discarded, and the extent of impregnation of the molded pulpproduct (the container) with the evaluation liquid was visuallyevaluated according to the following criteria.

4: Almost no oil stains observed in the interior of the bottom of themolded pulp container

3: No oil stains observed on the exterior of the bottom of the moldedpulp container

2: Oil stains observed on less than 5% of the exterior area of thebottom of the molded pulp container

1: Oil stains observed on 5% or more and less than 50% of the exteriorarea of the bottom of the molded pulp container

0: Oil stains observed on 50% or more of the exterior area of the bottomof the molded pulp container

[High-Temperature Water Resistance]

First, 100 ml of an evaluation liquid (tap water) at 90° C. was pouredinto a molded pulp product molded into a container shape, the moldedpulp product was left to stand still for 30 minutes, then the evaluationliquid was discarded, and the extent of impregnation of the molded pulpproduct (the container) with the evaluation liquid was visuallyevaluated according to the following criteria.

4: Almost no water stains observed in the interior of the bottom of themolded pulp container

3: No water stains observed on the exterior of the bottom of the moldedpulp container

2: Water stains observed on less than 5% of the exterior area of thebottom of the molded pulp container

1: Water stains observed on 5% or more and less than 50% of the exteriorarea of the bottom of the molded pulp container

0: Water stains observed on 50% or more of the exterior area of thebottom of the molded pulp container

[Air Permeance]

The air permeance (air resistance) at the bottom part of a molded pulpproduct molded into a container shape was measured in accordance withJIS P 8117 (2009) using an automatic Gurley densometer manufactured byYASUDA SEIKI SEISAKUSHO, LTD. (Product No. 323-AUTO, vent hole diameter28.6±0.1 mm). The measured value of air permeance was evaluatedaccording to the following criteria.

Evaluation Criteria

Excellent: 500 seconds or more

Good: 300 seconds or more

Fair: 100 seconds or more

Poor: less than 100 seconds

Synthesis Example 1

A reactor having a volume of 500 ml and equipped with a stirrer, athermometer, a reflux condenser, a dropping funnel, a nitrogen inlet,and a heater was provided, and 100 parts of a methyl ethyl ketone (MEK)solvent was added. Subsequently, while the solvent is stirred, a monomercomposed of 78 parts of stearyl acrylate (StA, melting point: 30° C.),16 parts of hydroxyethyl acrylate (HEA), and 6 parts of methacrylic acid(MAA) (the monomer being 100 parts in total) as well as 1.2 parts of aperbutyl PV (PV) initiator were added in this order, and the mixture wasmixed by being stirred for 12 hours in a nitrogen atmosphere at 65 to75° C. to carry out copolymerization. The solid content concentration ofthe resulting copolymer-containing solution was 50% by weight. When themolecular weight of the resulting copolymer was analyzed by gelpermeation chromatography, the weight-average molecular weight in termsof polystyrene was 230,000.

As a post-treatment, 142 g of a 0.3% aqueous NaOH solution was added to50 g of the resulting copolymer solution and dispersed, then MEK wasdistilled off under reduced pressure while heating the mixture by usingan evaporator, and thus a milky white water dispersion of a copolymerwas obtained (the content of the volatile organic solvent was 1% byweight or less). Moreover, ion-exchanged water was added to the waterdispersion, and thus a water dispersion having a solid contentconcentration of 15% by weight was obtained.

The melting point of the copolymer was 48° C.

Synthesis Example 2

A reactor having a volume of 500 ml and equipped with a stirrer, athermometer, a reflux condenser, a dropping funnel, a nitrogen inlet,and a heater was provided, and 100 parts of a methyl ethyl ketone (MEK)solvent was added. Subsequently, while the solvent is stirred, a monomercomposed of 78 parts of stearic acid amide ethyl acrylate (C18AmEA,melting point: 70° C.), 16 parts of hydroxybutyl acrylate (HBA, Tg: −40°C.), and 6 parts of dimethylaminoethyl methacrylate (DM) (the monomerbeing 100 parts in total) as well as 1.2 parts of a perbutyl PV (PV)initiator were added in this order, and mixed by being stirred for 12hours in a nitrogen atmosphere at 65 to 75° C. to carry outcopolymerization. The solid content concentration of the resultingcopolymer-containing solution was 50% by weight.

As a post-treatment, 142 g of a 0.4% aqueous acetic acid solution wasadded to 50 g of the resulting copolymer solution and dispersed, thenthe mixture was heated by using an evaporator to distill off MEK underreduced pressure, and thus a light brown copolymer-water dispersionliquid (the content of the volatile organic solvent was 1% by weight orless) was obtained. Moreover, ion-exchanged water was added to the waterdispersion, and thus a water dispersion having a solid contentconcentration of 15% by weight was obtained.

Example 1

2,400 g of a 0.5% by weight of the water dispersion of a mixture of 70parts of leaf bleached kraft pulp and 30 parts of needle bleached kraftpulp beaten to a freeness (Canadian Freeness) of 550 cc, was added withcontiguous stirring. Next, 1.2 g of calcium carbonate was added and keptstirring for 1 minute, and 2.4 g of a 5% solid aqueous solution ofamphoterized starch was added and kept stirring for 1 minute. Then, 0.72g of a 5% solid aqueous solution of alkyl ketene dimer (AKD) was addedand kept stirring for 1 minute, and subsequently 3.6 g of the waterdispersion of the fluorine-free copolymer of Synthesis Example 2 dilutedwith water to a solid content of 10% was added and kept stirring for 1minute.

The above pulp slurry was placed in a metal tank. In the lower part ofthe tank, a metal pulp mold with many suction holes was present with areticular body placed on top of the mold. From the side opposite to theside where the reticular body of the pulp mold was placed, thepulp-containing aqueous composition was suctioned and dehydrated throughthe pulp mold and the reticular body using a vacuum pump, and the solids(such as a pulp) contained in the pulp-containing aqueous compositionwere deposited on the reticular body to obtain a molded pulpintermediate. Next, the resulting molded pulp intermediate was dried byapplying pressure from top and bottom with metal male and female moldsheated to 60 to 200° C. As a result, a molded pulp product molded into acontainer shape was produced. Table 1 shows the results of evaluatingthe content of each component based on the pulp in the resulting moldedpulp product, as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

Example 2

2,400 g of a 0.5% by weight of the water dispersion of a mixture of 70parts of leaf bleached kraft pulp and 30 parts of needle bleached kraftpulp beaten to a freeness (Canadian Freeness) of 550 cc, was added withcontiguous stirring. Next, 0.6 g of calcium carbonate was added and keptstirring for 1 minute, and 1.2 g of cationized starch powder was addedand kept stirring for 1 minute. Then, 2.4 g of a 5% solid aqueoussolution of amphoterized starch was added and kept stirring for 1minute, and 0.72 g of a 5% solid aqueous solution of alkyl ketene dimer(AKD) was added and kept stirring for 1 minute. Subsequently, 3.6 g ofthe water dispersion of the fluorine-free copolymer of Synthesis Example2 diluted with water to a solid content of 10% was added and keptstirring for 1 minute.

Thereafter, molded pulp products were produced in the same manner as inExample 1, except that the above pulp slurry was used. Table 1 shows theresults of evaluating the content of each component based on the pulp inthe resulting molded pulp product, as well as high-temperatureoil-resistant characteristics, high-temperature water-resistantcharacteristics, and air permeance.

Example 3

The experiment was performed in the same manner as in Example 1, exceptthat 1.2 g of calcium carbonate in Example 2 was added, and 2.4 g ofcationized starch powder was added. Table 1 shows the results ofevaluating the content of each component based on the pulp in theresulting molded pulp product, as well as high-temperature oil-resistantcharacteristics, high-temperature water-resistant characteristics, andair permeance.

Example 4

The experiment was performed in the same manner as in Example 1, exceptthat 2.4 g of the water dispersion of the fluorine-free copolymer ofSynthesis Example 2 in Example 3 diluted with water to a solid contentof 10% was added. Table 1 shows the results of evaluating the content ofeach component based on the pulp in the resulting molded pulp product,as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

Example 5

The experiment was performed in the same manner as in Example 1, exceptthat 4.8 g of cationized starch powder in Example 4 was added. Table 1shows the results of evaluating the content of each component based onthe pulp in the resulting molded pulp product, as well ashigh-temperature oil-resistant characteristics, high-temperaturewater-resistant characteristics, and air permeance.

Example 6

The experiment was performed in the same manner as in Example 1, exceptthat calcium carbonate in Example 5 was not added, and 3.6 g of thewater dispersion of the fluorine-free copolymer of Synthesis Example 2diluted with water to a solid content of 10% was added. Table 1 showsthe results of evaluating the content of each component based on thepulp in the resulting molded pulp product, as well as high-temperatureoil-resistant characteristics, high-temperature water-resistantcharacteristics, and air permeance.

Example 7

The experiment was performed in the same manner as in Example 1, exceptthat a 5% solid aqueous solution of amphoterized starch in Example 5 wasnot added, and a 5% solid aqueous solution of alkyl ketene dimer (AKD)was not added. Table 1 shows the results of evaluating the content ofeach component based on the pulp in the resulting molded pulp product,as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

Example 8

The experiment was performed in the same manner as in Example 1, exceptthat 0.6 g of calcium carbonate in Example 1 was added. Table 1 showsthe results of evaluating the content of each component based on thepulp in the resulting molded pulp product, as well as high-temperatureoil-resistant characteristics, high-temperature water-resistantcharacteristics, and air permeance.

Example 9

The experiment was performed in the same manner as in Example 1, exceptthat 3.6 g of the water dispersion of the fluorine-free copolymer ofSynthesis Example 2 in Example 8 diluted with water to a solid contentof 10% was added and kept stirring for 1 minute, and then 6.0 g of thewater dispersion of the fluorine-free copolymer of Synthesis Example 1diluted with water to a solid content of 10% was added and kept stirringfor 1 minute. Table 1 shows the results of evaluating the content ofeach component based on the pulp in the resulting molded pulp product,as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

Example 10

The experiment was performed in the same manner as in Example 1, exceptthat a 5% solid aqueous solution of the alkyl ketene dimer (AKD) inExample 3 was not added. Table 1 shows the results of evaluating thecontent of each component based on the pulp in the resulting molded pulpproduct, as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

Comparative Example 1

The experiment was performed in the same manner as in Example 1, exceptthat calcium carbonate in Example 1 was not added, and 3.6 g ofstyrene-butadiene latex diluted with water to a solid content of 10% wasadded in place of the water dispersion of the fluorine-free copolymer ofSynthesis Example 2 diluted with water to a solid content of 10%. Table1 shows the results of evaluating the content of each component based onthe pulp in the resulting molded pulp product, as well ashigh-temperature oil-resistant characteristics, high-temperaturewater-resistant characteristics, and air permeance.

Comparative Example 2

The experiment was performed in the same manner as in Example 1 exceptthat 3.6 g of styrene-butadiene latex diluted with water to a solidcontent of 10% was added in place of the water dispersion of thefluorine-free copolymer of Synthesis Example 2 in Example 2 diluted withwater to a solid content of 10%. Table 1 shows the results of evaluatingthe content of each component based on the pulp in the resulting moldedpulp product, as well as high-temperature oil-resistant characteristics,high-temperature water-resistant characteristics, and air permeance.

TABLE 1 Ex. Ex. Ex. Ex. Ex. Com. Com. Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 6 78 9 10 Ex. 1 Ex. 2 Particles Inorganic Calcium solid %/  10%   5%  10% 10%  10% 10%   5%   5% 10%   5% Particles carbonate pulp OrganicCationized solid %/  10%  20%  20%  40%  40% 40% 20%  10% Particlesstarch pulp Aqueous starch Amphoterized solid %/   1%   1%   1%   1%  1%   1%   1%   1%  1%   1%   1% solution starch pulp Water- Alkylketene dimer solid %/ 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3% 0.3%resistant (AKD) pulp agent Treatment Acrylic Syn. Ex. 1 solid %/   5%agent polymer pulp Syn. Ex. 2 solid %/   3%   3%   3%   2%   2%   2%  2%  3%   3%  3% pulp Styrene-butadiene latex solid %/   3%   3% pulpHigh-temp. oil- Corn oil 90° C. × 30 min.  3  3  4  3  4  4  4  2  3  4 0  0 resistance High-temp. water- Tap water 90° C. × 30  3  3  3  3  3 3  1  3  3  1  4  4 resistance min. Air permeance Evaluation Poor FairEx- Ex- Ex- Ex- Ex- Poor Poor Ex- Poor Fair cellent cellent cellentcellent cellent cellent Measured value (sec.) 37 161 701 718 801 797 78330 33 687 42 177

INDUSTRIAL APPLICABILITY

The oil-resistant agent of the present disclosure is applicable to avariety of paper, particularly paper for use in a food container and afood packaging material. The oil-resistant agent is externally orinternally, particularly internally incorporated into the paper.

What is claimed is:
 1. A paper oil-resistant agent which is added tointerior of paper, comprising: (1) a fluorine-free polymer, and (2) atleast one type of particles selected from inorganic particles or organicparticles, wherein an amount of the particles (2) is 1 to 99.9% byweight, based on the total weight of the fluorine-free polymer (1) andthe particles (2).
 2. The paper oil-resistant agent according to claim1, wherein the fluorine-free polymer (1) is an acrylic polymer.
 3. Thepaper oil-resistant agent according to claim 1, wherein thefluorine-free polymer has a repeating unit formed from (a) an acrylicmonomer having a long-chain hydrocarbon group, and the acrylic monomerhaving a long-chain hydrocarbon group (a) is a monomer represented byformula:CH₂═C(—X¹)—C(═O)—Y¹(R¹)_(k) wherein R¹ each is independently ahydrocarbon group having 7 to 40 carbon atoms, X¹ is a hydrogen atom, amonovalent organic group, or a halogen atom, Y¹ is a divalent to atetravalent group composed of at least one selected from a hydrocarbongroup having one carbon atom, —C₆H₄—, —O—, —C(═O)—, —S(═O)₂—, or —NH—,provided that a hydrocarbon group is excluded, and k is 1 to
 3. 4. Thepaper oil-resistant agent according to claim 3, wherein, in the acrylicmonomer having a long-chain hydrocarbon group (a), X¹ is a hydrogen atomor a methyl group.
 5. The paper oil-resistant agent according to claim3, wherein, in the acrylic monomer having a long-chain hydrocarbon group(a), the long-chain hydrocarbon group has 18 or more carbon atoms. 6.The paper oil-resistant agent according to claim 3, wherein the acrylicmonomer having a long-chain hydrocarbon group (a) is: (a1) an acrylicmonomer represented by formula:CH₂═C(—X⁴)—C(═O)—Y²—R² wherein R² is a hydrocarbon group having 7 to 40carbon atoms, X⁴ is a hydrogen atom, a monovalent organic group, or ahalogen atom, and y² is —O— or —NH—, and/or (a2) an acrylic monomerrepresented by formula:CH₂═C(—X⁵)—C(═O)—Y³—Z(—Y⁴—R³)_(n) wherein R³ each is independently ahydrocarbon group having 7 to 40 carbon atoms, X⁵ is a hydrogen atom, amonovalent organic group, or a halogen atom, Y³ is —O— or —NH—, Y⁴ eachis independently a group composed of at least one selected from a directbond, —O—, —C(═O)—, —S(═O)₂—, or —NH—, Z is a direct bond or a divalentor trivalent hydrocarbon group having 1 to 5 carbon atoms, and n is 1 or2.
 7. The paper oil-resistant agent according to claim 3, wherein theacrylic monomer having a hydrophilic group (b) is at least oneoxyalkylene (meth)acrylate represented by formula:CH₂═CX²C(═O)—O—(RO)_(n)—X³  (b1)CH₂═CX²C(═O)—O—(RO)_(n)—C(═O)CX²═CH₂  (b2), orCH₂═CX²C(═O)—NH—(RO)_(n)—X³  (b3) wherein X² is a hydrogen atom or amethyl group, X³ is a hydrogen atom or an unsaturated or saturatedhydrocarbon group having 1 to 22 carbon atoms, R each is independentlyan alkylene group having 2 to 6 carbon atoms, and n is an integer of 1to
 90. 8. The paper oil-resistant agent according to claim 3, whereinthe fluorine-free polymer further comprises a repeating unit formed from(c) a monomer having an olefinic carbon-carbon double bond and having ananion donating group or a cation donating group, other than the monomers(a) and (b).
 9. The paper oil-resistant agent according to claim 8,wherein the anion donating group is a carboxyl group, or the cationdonating group is an amino group.
 10. The paper oil-resistant agentaccording to claim 3, wherein an amount of the repeating unit formedfrom the acrylic monomer having a long-chain hydrocarbon group (a) is 30to 90% by weight, based on a copolymer, and an amount of the repeatingunit formed from the acrylic monomer having a hydrophilic group (b) is 5to 70% by weight, based on the copolymer.
 11. The paper oil-resistantagent according to claim 1, wherein the inorganic particles are made ofat least one selected from calcium carbonate, talc, kaolin, clay, mica,aluminum hydroxide, barium sulfate, calcium silicate, calcium sulfate,silica, zinc carbonate, zinc oxide, titanium oxide, bentonite, and whitecarbon, and the organic particles are made of at least one selected frompolysaccharides and thermoplastic resins.
 12. The paper oil-resistantagent according to claim 1, wherein the organic particles are insolublein water at 40° C.
 13. The paper oil-resistant agent according to claim1, wherein the inorganic particles are calcium carbonate, and theorganic particles are starch.
 14. The paper oil-resistant agentaccording to claim 1, wherein the particles (2) comprises the organicparticles.
 15. The paper oil-resistant agent according to claim 1,further comprising a liquid medium which is water or a mixture of waterand an organic solvent.
 16. Oil-resistant paper comprising the paperoil-resistant agent according to claim 1, in interior of the paper. 17.The oil-resistant paper according to claim 16, which is a molded pulpproduct.
 18. The oil-resistant paper according to claim 16, which is afood packaging material or a food container.
 19. A method for producingoil-resistant paper, comprising: preparing a formulated pulp slurry byadding the oil-resistant agent according to claim 1 to a slurry in whichpulp is dispersed in an aqueous medium, making an oil-resistant paperintermediate, followed by dehydrating and then drying to obtain theoil-resistant paper.